The present invention relates to joining conductive materials, and more particularly to an apparatus for joining conductive materials by friction stir welding.
Similar and dissimilar conductive material components, such as bus bars, bus bar joints or bus bar plug-in connection points in electrical busway systems, are joined by conventional welding methods such as gas-metal arc welding (GMAW) or metal inert (MIG) welding. This joining technique causes excess weld metal to form on the bus bar parts, which require additional time and expense for the removal thereof.
Additionally, the GMAW method requires the use of a filler wire. However, filler wire typically has a lower conductivity than the bus bar material, thereby creating a joint that is lower in conductivity and strength than the bus bar joints that are being welded together. This lower conductivity causes the resistivity of the joint to be higher than the original conductive material, which in turn increases the heat dissipated at the joints.
Accordingly, there is a need for an improved apparatus for joining similar or dissimilar conductive materials that minimizes or eliminates conductivity discrepancy between the joint and the original conductive material. Additionally, there is a need for an apparatus that will join similar or dissimilar conductive materials without producing excess weld metal.
An apparatus is provided for joining electrically conductive materials by friction stir welding. The apparatus includes a shaft portion for being received by a rotation imparting apparatus, such as a power drill. The shaft portion also includes a second end having a cut-away portion configured for deflecting plasticized material during friction stir welding. A pilot extends from the second end formed of a material harder than said electrically conductive material. The pilot is configured and dimensioned for friction stir welding electrically conductive members together.
During operation, the apparatus is rotated while the pilot is inserted in a joint between electrically conductive members. While rotating, the apparatus is translated across the joint. A strong, low resistance friction stir weld is formed between the electrically conductive members.
The above discussed and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description and drawings.